Method of making and installing a laminated product

ABSTRACT

A coating or rubber base elastomeric material is provided on the bottom ply of the laminate and completed by subsequently hot pressing the various laminate plies to achieve bonding. The rubber coating functions as an adhesive layer when the laminate is applied to a substrate which is prime coated with a similar rubber base coating modified with an adhesive binder. Both prime coating and laminate coating are dry, firm and non-tacky. Adhesive bonding is achieved by mating the two coated surfaces.

United States Patent [1 1 Haigh Nov. 6, 1973 METHOD OF MAKING ANDINSTALLING A LAMINATED PRODUCT {75] Inventor: John M. I-Iaigh, Peabody,Mass.

[73] Assignee: Parkwood Laminates, lnc.,

Wakefield, Mass.

[22] Filed: May 9, 1969 [21] Appl. No.: 823,274

[52] U.S. C1 156/71, 156/182, 156/241, 156/289, 156/308, 156/309,156/323, 156/338 [51] Int. Cl E04f 13/00 [58] Field of Search 156/239,241, 278, 156/289, 308, 309, 320, 323, 338, 182, 71

[56] References Cited UNITED STATES PATENTS 156/278 Strachan 156/289Boyce 7/1970 Hartzell et a1. 1/1956 2,599,359 6/1952 Banks et a1.156/308 2,266,699 12/1941 Williamson..... 156/278 2,680,700 6/1954Meyers 156/289 3,135,647 6/1964 Wheeley 156/247 Primary Examiner-Carl D.Quarforth Assistant Examiner-F. M. Gittes Attorney-Dawson, Tilton,Fallon and Lungmus [57'] ABSTRACT A coating or rubber base elastomericmaterial is provided on the bottom ply of the laminate and completed bysubsequently hot pressing the various laminate plies to achieve bonding.The rubber coating functions as an adhesive layer when the laminate isapplied to a substrate which is prime coated with a similar rubber basecoating modified with an adhesive binder. Both prime coating andlaminate coating are dry, firm and nontacky. Adhesive bonding isachieved by mating the two coated surfaces.

2 Claims, 2 Drawing Figures Pmminnuv 6 ms 3.770.536

COATING INVENTOR JOHN M HA lGH METHOD OF MAKING AND INSTALLING ALAMINATED PRODUCT BACKGROUND OF THE INVENTION Laminated productsareconsidered to be structured materials having various diverse componentsbonded together to provide a wide variety of functional and/ordecorative properties.

Generally, the laminates of this invention have both decorative andfunctional components and are used as eye-pleasing surface coverings onwalls, furniture, counter-tops, and floors. The style-conscious consumertoday demands a variety of decorator colors, designs, and materials forsurface applications that were unheard of a decade ago. The resultingshow surfaces of decorative laminates have been upgraded immenselythrough the use of new designs and of new materials. As well asproviding an appealing surface for his product, the laminator must alsoprovide certain functional properties such as dimensional strength,water resistance, wear resistance and in general, the functionalpropertiesthat result in the product having a degree of permanence onceit is installed. In order to obtain the desired functional anddecorative properties in his product, the laminator combines variousplies having very different physical properties. The normal combiningprocess used in the industry involves laying up the various plies of thelaminate on press plates and applying pressure and temperatureto fusethe various components into-an integral product.

An inherent problem in multiple ply laminates is the variation indimensional stability between the various plies of the laminate. Avariation in dimensional stability within the finished laminate resultsin the laminate having a tendency to change shape and to curl. It iswith specific reference to the application of curled or bowed laminatedproducts that this disclosure is involved.

1 It is a recognized fact that when one of the ply components of alaminate loses or gains moisture at a faster rate than the'remainder ofthe laminate structure, either tension or compression stresses are setup that can cause laminate curl. Many different laminate contstructionsexhibit curl phenomena, due to internal stress, as will be readilyrecognized by those familiar with the decorative laminate industry. Theinvention is practiced not by reducing internal stresses within alaminate but rather to provide a novel method for readily applyingcurled laminates to various substrates. In fact, the invention takesadvantage of the fact that it is highly desirable to incorporate certainmaterials within a laminate that have a wide variation in dimensionalstability relative to moisture content. A pertinent example of alaminate having components of different dimensional stability is a woodveneer-vinyl plastic floor covering product. The true beauty of naturalwood in veneer form is incorporated in the laminate for its decorativeproperties. The wood veneer is laminated to flooring grade polyvinylchloride (PVC) sheeting. The PVC sheeting is less expensive than thewood veneer and has desirable functional properties of strength andresilience. However, it is recognized that wood veneer swells andshrinks under variable moisture conditions to a much greater extent thanPVC sheeting. Hence, a wood veneer-vinyl plastic floor tile has atendency to curl.

The accepted industry practice for laying floor tile, of which PVC is amajor component, is to cover the substrate or floor with a layer ofmastic cement that will firm up and harden as it dries. While the masticcement is still wet and pliable, the floor tiles are set into the masticcement and usually rolled with a weight to insure adequate contactbetween the tiles and the cement. When the cement hardens, usuallywithin two days, the tiles are firmly imbedded in the cement andattached to the floor. While this system is satisfactory for vinyl andvinyl-asbestos tiles, which do not have greatly different componentsregarding dimensional stability and have a tendency to lay flat and notcurl, it is not satisfactory for tiles that have components of differentdimensional stability, resulting in curl, and characteristic of the woodveneer-vinyl tile.

When an attempt is made to set the curled tile into a mastic cement, thetile hasa tendency to return to its curled shape, resulting in adeficiency of mastic in the curled-up area and the overall result is anon-flat installation with cement deficiencies in certain areas thatinfluence the permanence of the installation. When attempts are made toregulate the moisture content of the variable component, such as woodveneer, so that the tile is flat (i.e., not curled), when installed,problems also occur. While the tile may initially be flat when set intothe mastic cement, the dimensionally unstable component such as the woodveneer will soon change its moisture content, depending on atmospherichumidity conditions and tends to curl. Curling stresses usually beginbefore the mastic cement has hardened sufficiently to hold the curlingtile in place with the result that'the tile again is not flat and isdeficient in cement where it curled.

In dealing with dimensionally unstable products such as curled tiles,the installers have resorted to allowing the cement to dry to a highdegree of tack before setting in the tiles. The problem with thisapproach is that the more the cement dries the harder it is to obtainadequate contact and sealing of the tiles in the cement. Consequently, agreat deal of pressure and time (subjectively, patience) are requird toinstall curled tiles by this method. The overall result isunsatisfactory due to the narrow open time of the adhesive, when it isdried enough.

Another approach used by installers with dimensionally unstable orcurled tiles is to use a contact cement system. This system requiresthat both the substrate or floor and the tile be coated with the sameadhesive. After the adhesive on the tile and the floor has dried thetile is placed in contact with the floor. This system will hold downcurled tiles. However, the process is very time consuming and expensiveto the extent that it is rarely utilized. The contact cement systemrequires that each individual tile be coated and this is time consuming.The contact cement is solvent based, hence, both toxic and ignitable.Also the contact system does not allow for movement or repositioning ofthe tiles once they are laid.

Recognizing that it is highly desirable to use dimensionally unstablematerials such as wood veneer and dimensionally stable materials such asflooring grade PVC sheeting in the same laminate structure, it would bemost advantageous for installers to be able tosimply install curledlaminates without the shortcomings and limitations of the conventionaladhesive systems referred to above.

Consequently, it is an object of this invention to provide a laminatedproduct containing a dimensionally unstable component susceptible tocurl which can be applied to various substrates with an ease ofinstallation heretofore unobtainable.

Another object of this invention is to provide a method for applyingdimensionally unstable laminates (as of a cellulosic ply such as woodveneer and a thermoplastic such as polyvinyl chloride) which isessentially free of the limitations and short comings normallyassociated with the installation of curled laminates.

A further object of this invention is to provide a novel method formanufacturing a laminate that has an inchoate adhesive coating on thebonding surface of the laminate.

Another object of this invention is to provide an improved laminateinstallation method that is faster and cleaner than was heretoforeobtainable.

An additional object of this invention is to provide a laminateinstallation method whereby the open time of the adhesive is notcritical.

Other objects and advantages of this invention will be apparent from theensuing description and the appended claims.

DETAILED DESCRIPTION The invention is described in conjunction with theaccompanying drawing in which FIG. 1 is a perspective view of alaminated product, partly broken away to show the inventiveconstruction; and

FIG. 2 is an exploded elevational view of the FIG. 1 product. i

The invention is practiced through the use of an improved method ofmanufacturing and applying laminated products. This method includes:

1. Applying a rubber base elastomeric coating to the exterior surface ofthe bottom ply of the laminate and subsequently drying this coating to anon-tacky state.

2. Laying up the various components of the laminate structure so thatsaid coating on the bottom ply is the exterior surface of the laminatestructure and adjacent to a flexible release sheet.

3. Applying heat and pressure to the assembled laminate structure for aperiod of time sufficient to bond together said various components ofthe laminate structure.

4. Removing from the press the laminated structure containing a bondableback, in the form of the rubber base elastomeric coating, the bondableback being weakly attached to the release sheet.

5. Preparing for the application of the bondable back laminatedstructure by applying to the application substrate a primer coatingincluding the rubber base elastomeric coating and an adhesive binder,the primer coating being allowed to dry tack-free.

6. Applying the bondable back laminated structure by removing therelease sheet from the bondable back laminate and contacting thelaminated structure with the primer. coating on the substrate.

Pursuant to this invention, the application ofa rubber base elastomericcoating to the exterior ply component of the laminate structure hasdecided advantages. In the first place, the coating will effect anactual adhesive bond when it is contacted with a similar material suchas the primer coating on the substrate even though the laminate coatingis non-tacky and dry and exhibits nonadhesive characteristics todissimilar materials. The phenomena of contact grab or the ability ofrubber adhesives to bond to themselves when dry and nontacky ischaracteristic of certain rubber adhesives, most notably natural rubberlatex from the Hevea Brasiliensis species of tree. Natural rubber latexis the preferred rubber base elastomeric for both the laminate plycoating and the substrate primer coating due to its ability to retainits adhesive bonding potential to itself or a similar material forextended periods of time. Laminate ply coatings as disclosed in thisinvention have provided adhesive bonds adequate to hold down curledlaminates when they were installed over one year after manufacture. Inorder to extend the adhesive potential of the rubber laminate coating,it has been found advantageous to add a rubber antioxidant additive tothe coating.

It is a unique and unexpected discovery of this invention that rubbercoatings on the laminate ply will withstand laminating pressures andtemperatures and still have an adhesive bond potential for extendedtimes prior to actual product application. Pursuant to this invention, anatural rubber latex coating containing an antioxidant withstood alaminating cycle of 1,000 psi at 280 F. for 25 minutes and stilladequately held down the curled laminate made using this cycle wheninstalled one year after being manufactured.

An additional unique result of this invention is that it has beendiscovered that the laminating cycle greatly increases the bond betweenthe rubber coating and the exterior laminate ply. It was recognized thatwhile natural and unmodified rubbers form strong bonds to themselves andsimilar materials, their adhesion to dissimilar materials is low.Attempts to increase adhesion of rubber elastomers to dissimilarmaterials resulted in a decrease in the adhesive bonding potential tothemselves or similar materials. Consequently, in order to obtainmaximum adhesion potential and capability, relative to time, in thelaminate coating, it was deemed desirable not to add modifying bondingagents for securing the attachment of the rubber coating to thelaminate. In light of this, it was unexpected to find that thelaminating cycle causes a strong bond to form between the unmodifiedrubber coating and the laminate during the press cycle. In allprobability the bond between the rubber coating and the laminate that isinduced in the press cycle is the result of a pressure-vulcanizingeffect caus ing a mechanical bond at the rubber coating-laminateinterface.

As indicated above, the practice of this invention allows the majorportion of the total adhesive required for the installation of thelaminate product to be incorporated in the product during themanufacturing process. By way of example, the product of the inventionis described in the manufacture of a wood veneer vinyl flooring productas schematically pictured in the drawing. The various ply components ofthe laminate structure are, proceeding from top to bottom: 1 1 is a 14mil clear vinyl film; 12 is a 1/85 inch wood veneer; 13 is a 4 milopaque vinyl film; 14 is a 1 mil aluminum foil; 15 is a 45 mil flooringgrade vinyl; and 16 is a 15 mil asbestos felt. It is clear to thoseskilled in the art that the wood veneer component will show a degree ofdimensional instability significantly different from the remainingcomponents. The asbestos felt ply, being the exterior applicationsurface of the laminate, is thesurface to which the rubber coating isapplied. Natural rubber latex incorporating an antioxidant being thepreferred embodiment of this invention for coating the exterior laminateply, is normally supplied as a water base emulsion and is readilyapplied to the outside surface of the asbestos felt by simple spreadingdevices such as a roll coater. Preferably, 5 to lbs. of dry coating isapplied to each 1000 square feet of asbestos felt. Normal hotair orinfrared heaters can be used to dry the rubber coating. Drying is fairlyrapid as it is preferred to apply the coating at 50 percent solids,although advantageous results are obtained with emulsions havingfromabout 25 percent to about 75 percent solids. The dried coating is firmand non-tacky and will not adhere to dissimilar surfaces. Dissimilarsurfaces are further characterized as not being of a similar compositionto the rubber coating. The rubber coated asbestos felt is laid up in itscorrect position in the laminate structure with the rubber coating beingthe exterior surface. Between the rubber coating and the press plate orplaten is placed a flexible release-treated sheet. The preferred releasesheet is a 40 lb. silicone treated parchment which will remain looselyattached to the rubber coating until the laminated product is ready forinstallation.

The laminate as described above and depicted schematically in FIG. 2 isplaced between press platens and pressed at 300 psi and 275 F. forminutes, resulting in a good laminate bond between all laminate plies.Temperatures in the range of about 200 F. to about 400 F. may beemployed to advantages with pressures in the rangeof about 100 to 1,500psi. from the press and prepared for product finishing and shipment.

Having manufactured a laminate containing a dimensionally unstablecomponent, the result of which tends to induce curl in the product, andincorporating an inchoate adhesive on the exterior surface of thelaminate, the further teaching of this invention shows how the inchoateadhesive is caused to securely attach to a substrate during theapplication of the product in a simple manner sufficient to hold downand maintain with a degree of performance the curled product. The uniquecharacteristic of the rubber coating on the finished laminate is that itwill form a strong bond when contacted to a similar material.Consequently, the installation of the rubber coated laminate of thisdisclosure is readily accomplished with an ease heretofore unknown tothe art by simply'prime coating the installation substrate with asimilar modified rubber, allowing the prime coating to dry completelyand simply contacting with pressure the rubber coated laminate and theprime coating. Inasmuch as both the prime coating on the applicationsubstrate and the coating on the laminate are both completely dry andfirm, no movement takes place in the adhesive when the laminate is setin place. While lack of adhesive movement during bond is desirable inmany applications, it is essential during the bond formation andapplication of curled laminates. Obviously, if the adhesive is capableof movement when a curled or nonflat laminate is set in place theadhesive will tend to move and stretch as the laminate resumes a curledposition where the stresses in the laminate are in equilibrium. It canreadily be seen from the foregoing why conventional mastic cements thatrequire the laminate or tile to be set in place before the mastic hasdried and while it is still capable of movement are unsatisfactory forcurled laminates or tiles. It will be obvious to those skilled in theart of laminate installation, such as wall paneling and floor tiles,that the ease of installation of the product and method of thisdisclosure represents a dramatic and time saving contribution to theart.

In further defining the nature of the substrate prime coating it shouldbe again mentioned that rubber base, and particularly natural rubberbase unmodified latices exhibit low adhesion values to dissimilarmaterials such as substrates to which the laminate will be applied. Itis because of this low adhesion factor that it has been foundadvantageous to good substrate adhesion to incorporate a compatibleadhesive binder along with the rubber base in the prime coating.Examples of adhesive binders that are compatible with rubber baseadhesives are well known in the art. However, to mention a few that havebeen found to be satisfactory are the acrylic emulsions, and the watersoluble proteins such as casein and soya protein. While various amountsof the adhesive binder can be incorporated in the prime coating, it ispreferred to use between 10 percent and 50 percent of adhesive binder,based on the weight of the rubber component in the primer coating.

By way of example, the wood veneer-vinyl flooring tile previouslydescribed and depicted in FIG. 1 was cut into. 9 inch X 9 inch tiles andinstalled by the method of this disclosure. The tiles exhibited adefinite concave curl and would spring back to their original curlposition when attempts were made to lay them flat. In the method of thisdisclosure substrates of both underlayment grade plywood and smoothcement were prime coated with 12 lb. dry weight per 1,000 square feet ofa coating consisting of 100 parts natural rubber latex with antioxidantand 25 parts acrylic binder. The prime coating was a 60 percent solidswater emulsion and air dried tack-free in Va hour.

This application of the tiles was accomplished by removing theprotective release sheet and contacting the tiles to the prime coatedsubstrate. An immediate and strong bond was obtained sufficient to holddown and maintain down the curled tiles on both the plywood and thecement. As an indication of the degree of open time with this system,the prime coating was allowed to age on the substrate for three weeksprior to application of the tiles. Again completely adequate hold downadhesive bonds were obtained between the tiles and the aged prime coatedsubstrates. Prior to this invention, no adhesive system has beenavailable for installing laminates that exhibited an open time of morethan a few hours.

In summary, the invention makes use of a product assembled from aplurality of plies. One ply may be a cellulosic material arranged togive the appearance of natural wood. Exemplary of this is a wood veneer.Another of the plies is a thermoplastic material readily integrated withwood veneer, and a contemporary, inex pensive film for this purpose ispolyvinyl chloride. A third ply constituting the bottom facing ply wherethe product is to be installed as a floor tile is asbestos or likecoating-receptive material.

For the elastomeric coating, I employ from about 5 pounds to about 15pounds (on a dry basis) for each 1,000 square feet of product. Thecoating is applied to the asbestos or like adhesive-receptive ply in theform of an aqueous emulsion having from about 25 percent to aboutpercent solids. Excellent results are obtained with a 50 percentemulsion. The emulsion, in its solid content, is substantially therubber base elastomer fortified with from about 1 percent to about 10percent of an antioxidant material. Various rubber antioxidants areknown to this art, and thus far I have ascertained no criticality incharacter of the antioxidant, employing commercially available productstherefor.

After the elastomeric coating has been applied to the asbestos ply, thesame is dried to a non-tacky condition, advantageously, by hot air orinfrared lamps. The coated asbestos ply and the other plies areassembled in face-to-face, contacting condition, and installed in apress. A release material, such as a silicone-treated parchment of 40pound ream weight, is interposed between one platen of the press and theelastomeric coating.

A variety of integrating conditions may be employed, including pressuresof the order of 100 to about 1,500 psi, with a preferred range beingabout 300 psi to about 1,000 psi. The other parameters of heat and timemay range from about 200 F. to about 400 F., and from about 10 minutesto about 30 minutes, depending to a certain extent on thecharacteristics of the press.

The prime coating applied to the substrate also is advantageously in therange of about five pounds to about pounds (dry basis) to about 1,000square feet. This is employed in the form of an aqueous emulsion havingfrom about 25 percent to about 75 percent solids, with the preferredrange being 50 percent to about 60 percent solids. The solids content ofthe aqueous emulsion includes, as above, a few per cent of anantioxidant material, and from about 5 percent to about 50 percent of abinder such as the acrylic material, casein or soya protein mentionedabove. Preferably, the percentage of the binder is of the order of 25percent of the weight of the rubber base elastomer. Following theteachings set forth above, I find the invention capable of providing astrong union between the laminated product and the substrate even afterone week has elapsed following the application of the prime coat to thesubstrate and before the laminated product is applied to the prime coat.

I claim:

1. A method of manufacturing and installing a laminated product as acovering for walls, floors, and fumiture, comprising applying from about5 to about 15 pounds of a 25-75 percent emulsion of a rubber baseelastomeric coating having from about 1 percent to about 10 percent ofan antioxidant therein to each 1,000 square feet of a surface of anasbestos felt ply to be incorporated into said product, drying saidcoating to a non-tacky state, assemblying a ply of thermoplasticmaterial in contacting relation with said asbestos felt ply, and withsaid coating facing outwardly, assembling a plurality of plies adjacentsaid thermoplastic material ply, one of the plies in saidplurality beingconstructed of a material having a dimensional stability different fromsaid thermoplastic material ply, applying heat of the order of about200400 F. and pressure of the order of about -1,500 p.s.i. to the pliesto provide an integrated assembly while a releasesheet is positioned incontact with said coating, removing said release sheet and contactingthe coating of said asbestos felt ply to a substrate previously coveredwith a prime coating and dried to a tack-free condition and comprisingfrom about 1 percent to about 10 percent of an antioxidant, from about 5percent to about 50 percent of a binder, with the remainder being arubber base elastomeric material.

2. The method of claim 1 in which said rubber base elastomeric materialis a natural rubber latex derived from the I-Ievea Brasiliensis speciesof tree.

2. The method of claim 1 in which said rubber base elastomeric materialis a natural rubber latex derived from the Hevea Brasiliensis species oftree.